Human Thrombin Inhibitor, frozen. Mild inhibitor potency (1-10 BU/mL). Plasma Factor Inhibitor Plasmas are produced from normal human plasmas from which specific factors have been removed by selective affinity immuno-adsorption and an antibody inhibitory to the specific factor is added to provide neutralizing activity. These products can be used as a substitute for plasmas from patients that have developed neutralizing antibodies to coagulation factors and can be used as positive controls in factor inhibitor assays. The inhibitor potency is measured by standard Bethesda activity assay.